Dienes

Yesterday was the first day to talk about 1,3-dienes. We covered two major topics -- first was a treatment of the molecular orbitals that come into play with dienes. There are four molecular orbitals (conservation of orbitals as we can think of them as being derived from the four p-orbitals of the pi-system) and the two lowest in energy each contain a pair of electrons. The two higher energy orbitals are not populated by electrons. We also identified the HOMO and LUMO, and discussed the concept of phases in orbitals. All of this was (hopefully) reinforced by showing the orbitals of cyclopentadiene, as determined by Spartan.

The second topic was the addition of HBr to a diene. We saw the possibility of two products and determined how to tweak the conditions (temperature) to allow us to get the kinetic or thermodynamic product.

The picture is of the four molecular orbitals of a diene, just as we discussed in class. It should expand if you click on it.